Mesoscale Discussion 0409
NWS Storm Prediction Center Norman OK
0506 PM CDT Sun Apr 02 2017
Areas affected...Portions of the Mississippi Valley
Concerning...Severe potential...Watch possible
Valid 022206Z - 022330Z
Probability of Watch Issuance...60 percent
SUMMARY...A bow echo is approaching northern Mississippi early this
evening. While the air mass becomes less favorable for strong winds
with northeastward extent, some residual damaging-wind threat
downstream of Watch 110 may necessitate a small severe thunderstorm
watch.
DISCUSSION...A mature bow echo is accelerating northeastward through
northern portions of Watch 110 currently. Surface observations
depict a strong pressure rise/fall dipole pattern, with 2+ mb/hr
rises behind the line and 1.5-2 mb/hr falls ahead of the line. On
the nose of stronger southwesterly mid-level flow, this line should
continue to advance northeastward rapidly, likely reaching the
northern extent of Watch 110 by 23Z. While southeasterly flow is
transporting warm/moist air northward across Mississippi, the speed
of this bow will likely outpace significant low-level
destabilization, resulting in an eventual downturn in overall
intensity. Nonetheless, considering the current organization of the
line and the potential for enhanced mixing within a drier low-level
air mass to its northeast, some damaging-wind threat may extend
beyond the current watch. Therefore, new issuance could be needed
within the next hour across northern Mississippi.
..Picca/Edwards.. 04/02/2017
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...MEG...JAN...LZK...
LAT...LON 34109115 34539069 34639020 34678931 34558833 34378817
33858828 33748932 33729088 33829117 34109115
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